Some of you may know that radon has been an issue that could affect many homeowners every year and that it is the second leading cause of lung cancer after cigarette smoking. The focus for much of the past 30 years or so has been the basements of our homes. During those first 20-30 years of radon testing and mitigation, the Health Canada guideline for acceptable levels of radon was 800 Bq/m3. When the guideline was 800 Bq/m3, various areas around Canada were deemed to be high risk areas and other areas were deemed to be low risk areas.
The guideline for acceptable levels of radon in Canada has now dropped to 200 Bq/m3 – and the World Health Organization has published a 100 Bq/m3 guideline. In Canada, the guideline was reduced by 75% … so what does that mean?
Many commercial real estate clients we speak to reference the “high” risk versus “low” risk zones and perhaps do not consider their region as a concern with respect to radon. However, over the past few years, we have tested many commercial real estate buildings across Canada … and our results are somewhat alarming. We found that 25% of these tested buildings experienced radon concentrations higher than 200 Bq/m3 … but lower than 800 Bq/m3.
So in the past, these results would NOT have been considered elevated but now they exceed the new Health Canada guideline. The buildings shown to experience high levels of radon were located in Calgary, Prince George and Vancouver. Calgary has been thought to be a high risk radon area for quite some time but Vancouver and Prince George have not been thought to be high risk.
And these results are suggesting a few important facts:
- high levels of radon are not isolated to the lowest level of buildings – elevated radon was found in one building to be located on a level 2 levels from the lowest point in the building.
- ventilation is key – in poorly ventilated lower rooms/areas of commercial buildings, radon can accumulate to levels above guidelines.
- there does not need to be a basement for radon to be elevated – in 1 of our tested buildings that showed elevated radon, it was a slab on grade structure actually at the top of a small hill.
- concrete is a potential source of radon (radon may not just leak through cracks and openings in below grade walls/floors) – we observed poor ventilation combined with concrete wall/floors/ceiling/roof created elevated radon. In both of these buildings, elevated radon was not found below grade or at the lowest level.
So these results from Sterling IAQ and various other sources (Health Canada, CAREX Canada, etc.) do suggest that regular monitoring of radon in commercial buildings be conducted and mitigation take place if radon is found to be elevated.